It has been known for a long time to galvanize metals in order to protect them against corrosion.
This applies in particular to electrically conductive parts that have for a long time been covered in a fine layer of nickel.
Since nickel is a magnetic material, it is unsuitable for coating parts of electrical connectors, particularly those that are to convey high frequency signals.
Nickel has therefore been replaced by bronze, preferably white bronze of silvery appearance that is close to that of nickel, which material has sufficient electrical conductivity for the intended purpose, and has hardness that also protects coated parts effectively against the friction to which they can be subjected.
The drawback of untreated white bronze is its poor suitability for soldering.
To overcome that difficulty, it has been the practice to use activated soldering fluxes, thereby making it possible to solder appropriately, but requiring cleaning operations based on chlorofluorocarbons (CFCs).
Since the use of such substances has now been banned, solder joints on metal parts coated in white bronze are of poorer quality than before, and that can give rise to problems of reliability with connectors.